Annually, about 25,000 Veterans receive inpatient detoxification (detox) for substance use disorders (SUDs). Detox is not SUD treatment; it is the medical management of withdrawal to prevent complications, which may be fatal. Detox inpatients who enter SUD treatment and peer-based mutual-help groups (e.g., Alcoholics Anonymous) have much better outcomes (less substance use, HIV/HCV risk behaviors, homelessness, rehospitalizations, Emergency Department visits) than those who do not. However, because of their unique characteristics (severe and chronic addictions, co-morbidities, lack of resources, self- and provider-perceptions as unsuitable for treatment), most Veterans discharged from inpatient detox do not enter SUD treatment. For many Veterans, a pattern of repeated inpatient detox, with each episode incurring a higher risk of overdose, occurs. Therefore, in its Uniform Services Handbook, Mental Health Operations places major emphasis on increasing the rate of SUD treatment initiation and engagement following detox to benefit Veterans' outcomes and prevent more use of costly health care. The primary objective of this project is to implement and evaluate Enhanced Telephone Monitoring (ETM) as a new and innovative telehealth intervention to facilitate the transition from inpatient detox to SUD specialty treatment (residential, outpatient, pharmacotherapy), thereby improving Veterans' outcomes and decreasing VA health care costs. In a randomized trial at two sites (VA Palo Alto and Boston), we hypothesize that patients receiving ETM, compared to patients in usual care (UC), will be more likely to enter and engage in SUD treatment and mutual-help, have better SUD and related outcomes, and have fewer and delayed acute care episodes. This project will also conduct a formative evaluation of how to implement ETM VA-wide, focusing on diverse subgroups of Veterans. Further, it will conduct a Budget Impact Analysis (BIA) to determine the impact of ETM on total costs of VA care. We hypothesize that the higher costs associated with ETM (because patients will engage in SUD treatment) will be more than offset by its lower costs of acute care. Patients in the ETM condition will receive an in-person session while in detox, followed by coaching over the telephone for 3 months after discharge. The intervention will incorporate Motivational Interviewing, and Contracting, Prompting, and Reinforcing, to provide support while waiting for treatment, and facilitate entry into treatment and mutual-help, and improved responses to crises. Patients will be assessed at baseline and 3 and 6 months post-discharge for outcomes and non-VA health care; VA health care will be assessed with VA databases. GLMM analyses will be conducted to compare the UC and ETM groups on course of outcomes over time. The formative evaluation to inform the implementation of ETM will use the RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) framework. Semi-structured interviews will be conducted with inpatient detox staff and patients to yield facilitators of ETM implementation and modifiable barriers with associated action plans. For the BIA, costs of ETM will be measured through microcosting methods. For patients in both the ETM and UC groups, all inpatient, residential, outpatient, and pharmacy care will be measured from VA utilization and cost files. In summary, Mental Health Operations is committed to eradicating the dangerous, costly pattern of Veterans obtaining inpatient detox services but not receiving the SUD treatment they need. Telehealth interventions, a promising way to improve treatment access and outcomes by SUD patients, have not been utilized with the challenging population of detox inpatients before. In accordance with others in this CREATE, this project will help to accomplish Mental Health Operations' goal of implementing the Uniform Handbook by increasing Veterans' access to, engagement in, and benefit from, SUD treatment services, particularly among Veterans who are using VA medical services and need SUD services but are not receiving them.